Revert "Merge commit 'main-jb-2012.08.03-B4' into t114-0806"
[linux-2.6.git] / drivers / rtc / rtc-ds1307.c
index db6f3f0..c293d0c 100644 (file)
@@ -3,6 +3,7 @@
  *
  *  Copyright (C) 2005 James Chapman (ds1337 core)
  *  Copyright (C) 2006 David Brownell
+ *  Copyright (C) 2009 Matthias Fuchs (rx8025 support)
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
 
 
 
-/* We can't determine type by probing, but if we expect pre-Linux code
+/*
+ * We can't determine type by probing, but if we expect pre-Linux code
  * to have set the chip up as a clock (turning on the oscillator and
  * setting the date and time), Linux can ignore the non-clock features.
  * That's a natural job for a factory or repair bench.
- *
- * This is currently a simple no-alarms driver.  If your board has the
- * alarm irq wired up on a ds1337 or ds1339, and you want to use that,
- * then look at the rtc-rs5c372 driver for code to steal...
  */
 enum ds_type {
        ds_1307,
@@ -34,8 +32,13 @@ enum ds_type {
        ds_1338,
        ds_1339,
        ds_1340,
+       ds_1388,
+       ds_3231,
        m41t00,
-       // rs5c372 too?  different address...
+       mcp7941x,
+       rx_8025,
+       last_ds_type /* always last */
+       /* rs5c372 too?  different address... */
 };
 
 
@@ -43,6 +46,7 @@ enum ds_type {
 #define DS1307_REG_SECS                0x00    /* 00-59 */
 #      define DS1307_BIT_CH            0x80
 #      define DS1340_BIT_nEOSC         0x80
+#      define MCP7941X_BIT_ST          0x80
 #define DS1307_REG_MIN         0x01    /* 00-59 */
 #define DS1307_REG_HOUR                0x02    /* 00-23, or 1-12{am,pm} */
 #      define DS1307_BIT_12HR          0x40    /* in REG_HOUR */
@@ -50,12 +54,14 @@ enum ds_type {
 #      define DS1340_BIT_CENTURY_EN    0x80    /* in REG_HOUR */
 #      define DS1340_BIT_CENTURY       0x40    /* in REG_HOUR */
 #define DS1307_REG_WDAY                0x03    /* 01-07 */
+#      define MCP7941X_BIT_VBATEN      0x08
 #define DS1307_REG_MDAY                0x04    /* 01-31 */
 #define DS1307_REG_MONTH       0x05    /* 01-12 */
 #      define DS1337_BIT_CENTURY       0x80    /* in REG_MONTH */
 #define DS1307_REG_YEAR                0x06    /* 00-99 */
 
-/* Other registers (control, status, alarms, trickle charge, NVRAM, etc)
+/*
+ * Other registers (control, status, alarms, trickle charge, NVRAM, etc)
  * start at 7, and they differ a LOT. Only control and status matter for
  * basic RTC date and time functionality; be careful using them.
  */
@@ -67,6 +73,8 @@ enum ds_type {
 #      define DS1307_BIT_RS0           0x01
 #define DS1337_REG_CONTROL     0x0e
 #      define DS1337_BIT_nEOSC         0x80
+#      define DS1339_BIT_BBSQI         0x20
+#      define DS3231_BIT_BBSQW         0x40 /* same as BBSQI */
 #      define DS1337_BIT_RS2           0x10
 #      define DS1337_BIT_RS1           0x08
 #      define DS1337_BIT_INTCN         0x04
@@ -83,73 +91,225 @@ enum ds_type {
 #      define DS1337_BIT_OSF           0x80
 #      define DS1337_BIT_A2I           0x02
 #      define DS1337_BIT_A1I           0x01
+#define DS1339_REG_ALARM1_SECS 0x07
 #define DS1339_REG_TRICKLE     0x10
 
+#define RX8025_REG_CTRL1       0x0e
+#      define RX8025_BIT_2412          0x20
+#define RX8025_REG_CTRL2       0x0f
+#      define RX8025_BIT_PON           0x10
+#      define RX8025_BIT_VDET          0x40
+#      define RX8025_BIT_XST           0x20
 
 
 struct ds1307 {
-       u8                      reg_addr;
-       u8                      regs[8];
+       u8                      offset; /* register's offset */
+       u8                      regs[11];
+       u16                     nvram_offset;
+       struct bin_attribute    *nvram;
        enum ds_type            type;
-       struct i2c_msg          msg[2];
+       unsigned long           flags;
+#define HAS_NVRAM      0               /* bit 0 == sysfs file active */
+#define HAS_ALARM      1               /* bit 1 == irq claimed */
        struct i2c_client       *client;
-       struct i2c_client       dev;
        struct rtc_device       *rtc;
+       struct work_struct      work;
+       s32 (*read_block_data)(const struct i2c_client *client, u8 command,
+                              u8 length, u8 *values);
+       s32 (*write_block_data)(const struct i2c_client *client, u8 command,
+                               u8 length, const u8 *values);
 };
 
 struct chip_desc {
-       char                    name[9];
-       unsigned                nvram56:1;
        unsigned                alarm:1;
-       enum ds_type            type;
+       u16                     nvram_offset;
+       u16                     nvram_size;
+};
+
+static const struct chip_desc chips[last_ds_type] = {
+       [ds_1307] = {
+               .nvram_offset   = 8,
+               .nvram_size     = 56,
+       },
+       [ds_1337] = {
+               .alarm          = 1,
+       },
+       [ds_1338] = {
+               .nvram_offset   = 8,
+               .nvram_size     = 56,
+       },
+       [ds_1339] = {
+               .alarm          = 1,
+       },
+       [ds_3231] = {
+               .alarm          = 1,
+       },
+       [mcp7941x] = {
+               /* this is battery backed SRAM */
+               .nvram_offset   = 0x20,
+               .nvram_size     = 0x40,
+       },
 };
 
-static const struct chip_desc chips[] = { {
-       .name           = "ds1307",
-       .type           = ds_1307,
-       .nvram56        = 1,
-}, {
-       .name           = "ds1337",
-       .type           = ds_1337,
-       .alarm          = 1,
-}, {
-       .name           = "ds1338",
-       .type           = ds_1338,
-       .nvram56        = 1,
-}, {
-       .name           = "ds1339",
-       .type           = ds_1339,
-       .alarm          = 1,
-}, {
-       .name           = "ds1340",
-       .type           = ds_1340,
-}, {
-       .name           = "m41t00",
-       .type           = m41t00,
-}, };
-
-static inline const struct chip_desc *find_chip(const char *s)
+static const struct i2c_device_id ds1307_id[] = {
+       { "ds1307", ds_1307 },
+       { "ds1337", ds_1337 },
+       { "ds1338", ds_1338 },
+       { "ds1339", ds_1339 },
+       { "ds1388", ds_1388 },
+       { "ds1340", ds_1340 },
+       { "ds3231", ds_3231 },
+       { "m41t00", m41t00 },
+       { "mcp7941x", mcp7941x },
+       { "pt7c4338", ds_1307 },
+       { "rx8025", rx_8025 },
+       { }
+};
+MODULE_DEVICE_TABLE(i2c, ds1307_id);
+
+/*----------------------------------------------------------------------*/
+
+#define BLOCK_DATA_MAX_TRIES 10
+
+static s32 ds1307_read_block_data_once(const struct i2c_client *client,
+                                      u8 command, u8 length, u8 *values)
+{
+       s32 i, data;
+
+       for (i = 0; i < length; i++) {
+               data = i2c_smbus_read_byte_data(client, command + i);
+               if (data < 0)
+                       return data;
+               values[i] = data;
+       }
+       return i;
+}
+
+static s32 ds1307_read_block_data(const struct i2c_client *client, u8 command,
+                                 u8 length, u8 *values)
+{
+       u8 oldvalues[I2C_SMBUS_BLOCK_MAX];
+       s32 ret;
+       int tries = 0;
+
+       dev_dbg(&client->dev, "ds1307_read_block_data (length=%d)\n", length);
+       ret = ds1307_read_block_data_once(client, command, length, values);
+       if (ret < 0)
+               return ret;
+       do {
+               if (++tries > BLOCK_DATA_MAX_TRIES) {
+                       dev_err(&client->dev,
+                               "ds1307_read_block_data failed\n");
+                       return -EIO;
+               }
+               memcpy(oldvalues, values, length);
+               ret = ds1307_read_block_data_once(client, command, length,
+                                                 values);
+               if (ret < 0)
+                       return ret;
+       } while (memcmp(oldvalues, values, length));
+       return length;
+}
+
+static s32 ds1307_write_block_data(const struct i2c_client *client, u8 command,
+                                  u8 length, const u8 *values)
+{
+       u8 currvalues[I2C_SMBUS_BLOCK_MAX];
+       int tries = 0;
+
+       dev_dbg(&client->dev, "ds1307_write_block_data (length=%d)\n", length);
+       do {
+               s32 i, ret;
+
+               if (++tries > BLOCK_DATA_MAX_TRIES) {
+                       dev_err(&client->dev,
+                               "ds1307_write_block_data failed\n");
+                       return -EIO;
+               }
+               for (i = 0; i < length; i++) {
+                       ret = i2c_smbus_write_byte_data(client, command + i,
+                                                       values[i]);
+                       if (ret < 0)
+                               return ret;
+               }
+               ret = ds1307_read_block_data_once(client, command, length,
+                                                 currvalues);
+               if (ret < 0)
+                       return ret;
+       } while (memcmp(currvalues, values, length));
+       return length;
+}
+
+/*----------------------------------------------------------------------*/
+
+/*
+ * The IRQ logic includes a "real" handler running in IRQ context just
+ * long enough to schedule this workqueue entry.   We need a task context
+ * to talk to the RTC, since I2C I/O calls require that; and disable the
+ * IRQ until we clear its status on the chip, so that this handler can
+ * work with any type of triggering (not just falling edge).
+ *
+ * The ds1337 and ds1339 both have two alarms, but we only use the first
+ * one (with a "seconds" field).  For ds1337 we expect nINTA is our alarm
+ * signal; ds1339 chips have only one alarm signal.
+ */
+static void ds1307_work(struct work_struct *work)
 {
-       unsigned i;
+       struct ds1307           *ds1307;
+       struct i2c_client       *client;
+       struct mutex            *lock;
+       int                     stat, control;
+
+       ds1307 = container_of(work, struct ds1307, work);
+       client = ds1307->client;
+       lock = &ds1307->rtc->ops_lock;
+
+       mutex_lock(lock);
+       stat = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
+       if (stat < 0)
+               goto out;
+
+       if (stat & DS1337_BIT_A1I) {
+               stat &= ~DS1337_BIT_A1I;
+               i2c_smbus_write_byte_data(client, DS1337_REG_STATUS, stat);
+
+               control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
+               if (control < 0)
+                       goto out;
 
-       for (i = 0; i < ARRAY_SIZE(chips); i++)
-               if (strnicmp(s, chips[i].name, sizeof chips[i].name) == 0)
-                       return &chips[i];
-       return NULL;
+               control &= ~DS1337_BIT_A1IE;
+               i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, control);
+
+               rtc_update_irq(ds1307->rtc, 1, RTC_AF | RTC_IRQF);
+       }
+
+out:
+       if (test_bit(HAS_ALARM, &ds1307->flags))
+               enable_irq(client->irq);
+       mutex_unlock(lock);
 }
 
+static irqreturn_t ds1307_irq(int irq, void *dev_id)
+{
+       struct i2c_client       *client = dev_id;
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+
+       disable_irq_nosync(irq);
+       schedule_work(&ds1307->work);
+       return IRQ_HANDLED;
+}
+
+/*----------------------------------------------------------------------*/
+
 static int ds1307_get_time(struct device *dev, struct rtc_time *t)
 {
        struct ds1307   *ds1307 = dev_get_drvdata(dev);
        int             tmp;
 
        /* read the RTC date and time registers all at once */
-       ds1307->msg[1].flags = I2C_M_RD;
-       ds1307->msg[1].len = 7;
-
-       tmp = i2c_transfer(to_i2c_adapter(ds1307->client->dev.parent),
-                       ds1307->msg, 2);
-       if (tmp != 2) {
+       tmp = ds1307->read_block_data(ds1307->client,
+               ds1307->offset, 7, ds1307->regs);
+       if (tmp != 7) {
                dev_err(dev, "%s error %d\n", "read", tmp);
                return -EIO;
        }
@@ -161,17 +321,17 @@ static int ds1307_get_time(struct device *dev, struct rtc_time *t)
                        ds1307->regs[4], ds1307->regs[5],
                        ds1307->regs[6]);
 
-       t->tm_sec = BCD2BIN(ds1307->regs[DS1307_REG_SECS] & 0x7f);
-       t->tm_min = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
+       t->tm_sec = bcd2bin(ds1307->regs[DS1307_REG_SECS] & 0x7f);
+       t->tm_min = bcd2bin(ds1307->regs[DS1307_REG_MIN] & 0x7f);
        tmp = ds1307->regs[DS1307_REG_HOUR] & 0x3f;
-       t->tm_hour = BCD2BIN(tmp);
-       t->tm_wday = BCD2BIN(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
-       t->tm_mday = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
+       t->tm_hour = bcd2bin(tmp);
+       t->tm_wday = bcd2bin(ds1307->regs[DS1307_REG_WDAY] & 0x07) - 1;
+       t->tm_mday = bcd2bin(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
        tmp = ds1307->regs[DS1307_REG_MONTH] & 0x1f;
-       t->tm_mon = BCD2BIN(tmp) - 1;
+       t->tm_mon = bcd2bin(tmp) - 1;
 
        /* assume 20YY not 19YY, and ignore DS1337_BIT_CENTURY */
-       t->tm_year = BCD2BIN(ds1307->regs[DS1307_REG_YEAR]) + 100;
+       t->tm_year = bcd2bin(ds1307->regs[DS1307_REG_YEAR]) + 100;
 
        dev_dbg(dev, "%s secs=%d, mins=%d, "
                "hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
@@ -196,112 +356,332 @@ static int ds1307_set_time(struct device *dev, struct rtc_time *t)
                t->tm_hour, t->tm_mday,
                t->tm_mon, t->tm_year, t->tm_wday);
 
-       *buf++ = 0;             /* first register addr */
-       buf[DS1307_REG_SECS] = BIN2BCD(t->tm_sec);
-       buf[DS1307_REG_MIN] = BIN2BCD(t->tm_min);
-       buf[DS1307_REG_HOUR] = BIN2BCD(t->tm_hour);
-       buf[DS1307_REG_WDAY] = BIN2BCD(t->tm_wday + 1);
-       buf[DS1307_REG_MDAY] = BIN2BCD(t->tm_mday);
-       buf[DS1307_REG_MONTH] = BIN2BCD(t->tm_mon + 1);
+       buf[DS1307_REG_SECS] = bin2bcd(t->tm_sec);
+       buf[DS1307_REG_MIN] = bin2bcd(t->tm_min);
+       buf[DS1307_REG_HOUR] = bin2bcd(t->tm_hour);
+       buf[DS1307_REG_WDAY] = bin2bcd(t->tm_wday + 1);
+       buf[DS1307_REG_MDAY] = bin2bcd(t->tm_mday);
+       buf[DS1307_REG_MONTH] = bin2bcd(t->tm_mon + 1);
 
        /* assume 20YY not 19YY */
        tmp = t->tm_year - 100;
-       buf[DS1307_REG_YEAR] = BIN2BCD(tmp);
+       buf[DS1307_REG_YEAR] = bin2bcd(tmp);
 
        switch (ds1307->type) {
        case ds_1337:
        case ds_1339:
+       case ds_3231:
                buf[DS1307_REG_MONTH] |= DS1337_BIT_CENTURY;
                break;
        case ds_1340:
                buf[DS1307_REG_HOUR] |= DS1340_BIT_CENTURY_EN
                                | DS1340_BIT_CENTURY;
                break;
+       case mcp7941x:
+               /*
+                * these bits were cleared when preparing the date/time
+                * values and need to be set again before writing the
+                * buffer out to the device.
+                */
+               buf[DS1307_REG_SECS] |= MCP7941X_BIT_ST;
+               buf[DS1307_REG_WDAY] |= MCP7941X_BIT_VBATEN;
+               break;
        default:
                break;
        }
 
-       ds1307->msg[1].flags = 0;
-       ds1307->msg[1].len = 8;
-
        dev_dbg(dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
                "write", buf[0], buf[1], buf[2], buf[3],
                buf[4], buf[5], buf[6]);
 
-       result = i2c_transfer(to_i2c_adapter(ds1307->client->dev.parent),
-                       &ds1307->msg[1], 1);
-       if (result != 1) {
-               dev_err(dev, "%s error %d\n", "write", tmp);
+       result = ds1307->write_block_data(ds1307->client,
+               ds1307->offset, 7, buf);
+       if (result < 0) {
+               dev_err(dev, "%s error %d\n", "write", result);
+               return result;
+       }
+       return 0;
+}
+
+static int ds1337_read_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+       struct i2c_client       *client = to_i2c_client(dev);
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+       int                     ret;
+
+       if (!test_bit(HAS_ALARM, &ds1307->flags))
+               return -EINVAL;
+
+       /* read all ALARM1, ALARM2, and status registers at once */
+       ret = ds1307->read_block_data(client,
+                       DS1339_REG_ALARM1_SECS, 9, ds1307->regs);
+       if (ret != 9) {
+               dev_err(dev, "%s error %d\n", "alarm read", ret);
                return -EIO;
        }
+
+       dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
+                       "alarm read",
+                       ds1307->regs[0], ds1307->regs[1],
+                       ds1307->regs[2], ds1307->regs[3],
+                       ds1307->regs[4], ds1307->regs[5],
+                       ds1307->regs[6], ds1307->regs[7],
+                       ds1307->regs[8]);
+
+       /*
+        * report alarm time (ALARM1); assume 24 hour and day-of-month modes,
+        * and that all four fields are checked matches
+        */
+       t->time.tm_sec = bcd2bin(ds1307->regs[0] & 0x7f);
+       t->time.tm_min = bcd2bin(ds1307->regs[1] & 0x7f);
+       t->time.tm_hour = bcd2bin(ds1307->regs[2] & 0x3f);
+       t->time.tm_mday = bcd2bin(ds1307->regs[3] & 0x3f);
+       t->time.tm_mon = -1;
+       t->time.tm_year = -1;
+       t->time.tm_wday = -1;
+       t->time.tm_yday = -1;
+       t->time.tm_isdst = -1;
+
+       /* ... and status */
+       t->enabled = !!(ds1307->regs[7] & DS1337_BIT_A1IE);
+       t->pending = !!(ds1307->regs[8] & DS1337_BIT_A1I);
+
+       dev_dbg(dev, "%s secs=%d, mins=%d, "
+               "hours=%d, mday=%d, enabled=%d, pending=%d\n",
+               "alarm read", t->time.tm_sec, t->time.tm_min,
+               t->time.tm_hour, t->time.tm_mday,
+               t->enabled, t->pending);
+
+       return 0;
+}
+
+static int ds1337_set_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+       struct i2c_client       *client = to_i2c_client(dev);
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+       unsigned char           *buf = ds1307->regs;
+       u8                      control, status;
+       int                     ret;
+
+       if (!test_bit(HAS_ALARM, &ds1307->flags))
+               return -EINVAL;
+
+       dev_dbg(dev, "%s secs=%d, mins=%d, "
+               "hours=%d, mday=%d, enabled=%d, pending=%d\n",
+               "alarm set", t->time.tm_sec, t->time.tm_min,
+               t->time.tm_hour, t->time.tm_mday,
+               t->enabled, t->pending);
+
+       /* read current status of both alarms and the chip */
+       ret = ds1307->read_block_data(client,
+                       DS1339_REG_ALARM1_SECS, 9, buf);
+       if (ret != 9) {
+               dev_err(dev, "%s error %d\n", "alarm write", ret);
+               return -EIO;
+       }
+       control = ds1307->regs[7];
+       status = ds1307->regs[8];
+
+       dev_dbg(dev, "%s: %02x %02x %02x %02x, %02x %02x %02x, %02x %02x\n",
+                       "alarm set (old status)",
+                       ds1307->regs[0], ds1307->regs[1],
+                       ds1307->regs[2], ds1307->regs[3],
+                       ds1307->regs[4], ds1307->regs[5],
+                       ds1307->regs[6], control, status);
+
+       /* set ALARM1, using 24 hour and day-of-month modes */
+       buf[0] = bin2bcd(t->time.tm_sec);
+       buf[1] = bin2bcd(t->time.tm_min);
+       buf[2] = bin2bcd(t->time.tm_hour);
+       buf[3] = bin2bcd(t->time.tm_mday);
+
+       /* set ALARM2 to non-garbage */
+       buf[4] = 0;
+       buf[5] = 0;
+       buf[6] = 0;
+
+       /* optionally enable ALARM1 */
+       buf[7] = control & ~(DS1337_BIT_A1IE | DS1337_BIT_A2IE);
+       if (t->enabled) {
+               dev_dbg(dev, "alarm IRQ armed\n");
+               buf[7] |= DS1337_BIT_A1IE;      /* only ALARM1 is used */
+       }
+       buf[8] = status & ~(DS1337_BIT_A1I | DS1337_BIT_A2I);
+
+       ret = ds1307->write_block_data(client,
+                       DS1339_REG_ALARM1_SECS, 9, buf);
+       if (ret < 0) {
+               dev_err(dev, "can't set alarm time\n");
+               return ret;
+       }
+
+       return 0;
+}
+
+static int ds1307_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+       struct i2c_client       *client = to_i2c_client(dev);
+       struct ds1307           *ds1307 = i2c_get_clientdata(client);
+       int                     ret;
+
+       if (!test_bit(HAS_ALARM, &ds1307->flags))
+               return -ENOTTY;
+
+       ret = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);
+       if (ret < 0)
+               return ret;
+
+       if (enabled)
+               ret |= DS1337_BIT_A1IE;
+       else
+               ret &= ~DS1337_BIT_A1IE;
+
+       ret = i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL, ret);
+       if (ret < 0)
+               return ret;
+
        return 0;
 }
 
 static const struct rtc_class_ops ds13xx_rtc_ops = {
        .read_time      = ds1307_get_time,
        .set_time       = ds1307_set_time,
+       .read_alarm     = ds1337_read_alarm,
+       .set_alarm      = ds1337_set_alarm,
+       .alarm_irq_enable = ds1307_alarm_irq_enable,
 };
 
-static struct i2c_driver ds1307_driver;
+/*----------------------------------------------------------------------*/
+
+static ssize_t
+ds1307_nvram_read(struct file *filp, struct kobject *kobj,
+               struct bin_attribute *attr,
+               char *buf, loff_t off, size_t count)
+{
+       struct i2c_client       *client;
+       struct ds1307           *ds1307;
+       int                     result;
+
+       client = kobj_to_i2c_client(kobj);
+       ds1307 = i2c_get_clientdata(client);
+
+       if (unlikely(off >= ds1307->nvram->size))
+               return 0;
+       if ((off + count) > ds1307->nvram->size)
+               count = ds1307->nvram->size - off;
+       if (unlikely(!count))
+               return count;
+
+       result = ds1307->read_block_data(client, ds1307->nvram_offset + off,
+                                                               count, buf);
+       if (result < 0)
+               dev_err(&client->dev, "%s error %d\n", "nvram read", result);
+       return result;
+}
+
+static ssize_t
+ds1307_nvram_write(struct file *filp, struct kobject *kobj,
+               struct bin_attribute *attr,
+               char *buf, loff_t off, size_t count)
+{
+       struct i2c_client       *client;
+       struct ds1307           *ds1307;
+       int                     result;
+
+       client = kobj_to_i2c_client(kobj);
+       ds1307 = i2c_get_clientdata(client);
+
+       if (unlikely(off >= ds1307->nvram->size))
+               return -EFBIG;
+       if ((off + count) > ds1307->nvram->size)
+               count = ds1307->nvram->size - off;
+       if (unlikely(!count))
+               return count;
+
+       result = ds1307->write_block_data(client, ds1307->nvram_offset + off,
+                                                               count, buf);
+       if (result < 0) {
+               dev_err(&client->dev, "%s error %d\n", "nvram write", result);
+               return result;
+       }
+       return count;
+}
+
+/*----------------------------------------------------------------------*/
 
-static int __devinit ds1307_probe(struct i2c_client *client)
+static int __devinit ds1307_probe(struct i2c_client *client,
+                                 const struct i2c_device_id *id)
 {
        struct ds1307           *ds1307;
        int                     err = -ENODEV;
        int                     tmp;
-       const struct chip_desc  *chip;
+       const struct chip_desc  *chip = &chips[id->driver_data];
        struct i2c_adapter      *adapter = to_i2c_adapter(client->dev.parent);
-
-       chip = find_chip(client->name);
-       if (!chip) {
-               dev_err(&client->dev, "unknown chip type '%s'\n",
-                               client->name);
-               return -ENODEV;
-       }
-
-       if (!i2c_check_functionality(adapter,
-                       I2C_FUNC_I2C | I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
+       int                     want_irq = false;
+       unsigned char           *buf;
+       static const int        bbsqi_bitpos[] = {
+               [ds_1337] = 0,
+               [ds_1339] = DS1339_BIT_BBSQI,
+               [ds_3231] = DS3231_BIT_BBSQW,
+       };
+
+       if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)
+           && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
                return -EIO;
 
-       if (!(ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL)))
+       ds1307 = kzalloc(sizeof(struct ds1307), GFP_KERNEL);
+       if (!ds1307)
                return -ENOMEM;
 
-       ds1307->client = client;
        i2c_set_clientdata(client, ds1307);
 
-       ds1307->msg[0].addr = client->addr;
-       ds1307->msg[0].flags = 0;
-       ds1307->msg[0].len = 1;
-       ds1307->msg[0].buf = &ds1307->reg_addr;
-
-       ds1307->msg[1].addr = client->addr;
-       ds1307->msg[1].flags = I2C_M_RD;
-       ds1307->msg[1].len = sizeof(ds1307->regs);
-       ds1307->msg[1].buf = ds1307->regs;
-
-       ds1307->type = chip->type;
+       ds1307->client  = client;
+       ds1307->type    = id->driver_data;
+       ds1307->offset  = 0;
+
+       buf = ds1307->regs;
+       if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
+               ds1307->read_block_data = i2c_smbus_read_i2c_block_data;
+               ds1307->write_block_data = i2c_smbus_write_i2c_block_data;
+       } else {
+               ds1307->read_block_data = ds1307_read_block_data;
+               ds1307->write_block_data = ds1307_write_block_data;
+       }
 
        switch (ds1307->type) {
        case ds_1337:
        case ds_1339:
-               ds1307->reg_addr = DS1337_REG_CONTROL;
-               ds1307->msg[1].len = 2;
-
+       case ds_3231:
                /* get registers that the "rtc" read below won't read... */
-               tmp = i2c_transfer(adapter, ds1307->msg, 2);
+               tmp = ds1307->read_block_data(ds1307->client,
+                               DS1337_REG_CONTROL, 2, buf);
                if (tmp != 2) {
                        pr_debug("read error %d\n", tmp);
                        err = -EIO;
                        goto exit_free;
                }
 
-               ds1307->reg_addr = 0;
-               ds1307->msg[1].len = sizeof(ds1307->regs);
-
                /* oscillator off?  turn it on, so clock can tick. */
                if (ds1307->regs[0] & DS1337_BIT_nEOSC)
-                       i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
-                               ds1307->regs[0] & ~DS1337_BIT_nEOSC);
+                       ds1307->regs[0] &= ~DS1337_BIT_nEOSC;
+
+               /*
+                * Using IRQ?  Disable the square wave and both alarms.
+                * For some variants, be sure alarms can trigger when we're
+                * running on Vbackup (BBSQI/BBSQW)
+                */
+               if (ds1307->client->irq > 0 && chip->alarm) {
+                       INIT_WORK(&ds1307->work, ds1307_work);
+
+                       ds1307->regs[0] |= DS1337_BIT_INTCN
+                                       | bbsqi_bitpos[ds1307->type];
+                       ds1307->regs[0] &= ~(DS1337_BIT_A2IE | DS1337_BIT_A1IE);
+
+                       want_irq = true;
+               }
+
+               i2c_smbus_write_byte_data(client, DS1337_REG_CONTROL,
+                                                       ds1307->regs[0]);
 
                /* oscillator fault?  clear flag, and warn */
                if (ds1307->regs[1] & DS1337_BIT_OSF) {
@@ -310,31 +690,95 @@ static int __devinit ds1307_probe(struct i2c_client *client)
                        dev_warn(&client->dev, "SET TIME!\n");
                }
                break;
+
+       case rx_8025:
+               tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
+                               RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
+               if (tmp != 2) {
+                       pr_debug("read error %d\n", tmp);
+                       err = -EIO;
+                       goto exit_free;
+               }
+
+               /* oscillator off?  turn it on, so clock can tick. */
+               if (!(ds1307->regs[1] & RX8025_BIT_XST)) {
+                       ds1307->regs[1] |= RX8025_BIT_XST;
+                       i2c_smbus_write_byte_data(client,
+                                                 RX8025_REG_CTRL2 << 4 | 0x08,
+                                                 ds1307->regs[1]);
+                       dev_warn(&client->dev,
+                                "oscillator stop detected - SET TIME!\n");
+               }
+
+               if (ds1307->regs[1] & RX8025_BIT_PON) {
+                       ds1307->regs[1] &= ~RX8025_BIT_PON;
+                       i2c_smbus_write_byte_data(client,
+                                                 RX8025_REG_CTRL2 << 4 | 0x08,
+                                                 ds1307->regs[1]);
+                       dev_warn(&client->dev, "power-on detected\n");
+               }
+
+               if (ds1307->regs[1] & RX8025_BIT_VDET) {
+                       ds1307->regs[1] &= ~RX8025_BIT_VDET;
+                       i2c_smbus_write_byte_data(client,
+                                                 RX8025_REG_CTRL2 << 4 | 0x08,
+                                                 ds1307->regs[1]);
+                       dev_warn(&client->dev, "voltage drop detected\n");
+               }
+
+               /* make sure we are running in 24hour mode */
+               if (!(ds1307->regs[0] & RX8025_BIT_2412)) {
+                       u8 hour;
+
+                       /* switch to 24 hour mode */
+                       i2c_smbus_write_byte_data(client,
+                                                 RX8025_REG_CTRL1 << 4 | 0x08,
+                                                 ds1307->regs[0] |
+                                                 RX8025_BIT_2412);
+
+                       tmp = i2c_smbus_read_i2c_block_data(ds1307->client,
+                                       RX8025_REG_CTRL1 << 4 | 0x08, 2, buf);
+                       if (tmp != 2) {
+                               pr_debug("read error %d\n", tmp);
+                               err = -EIO;
+                               goto exit_free;
+                       }
+
+                       /* correct hour */
+                       hour = bcd2bin(ds1307->regs[DS1307_REG_HOUR]);
+                       if (hour == 12)
+                               hour = 0;
+                       if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
+                               hour += 12;
+
+                       i2c_smbus_write_byte_data(client,
+                                                 DS1307_REG_HOUR << 4 | 0x08,
+                                                 hour);
+               }
+               break;
+       case ds_1388:
+               ds1307->offset = 1; /* Seconds starts at 1 */
+               break;
        default:
                break;
        }
 
 read_rtc:
        /* read RTC registers */
-
-       tmp = i2c_transfer(adapter, ds1307->msg, 2);
-       if (tmp != 2) {
+       tmp = ds1307->read_block_data(ds1307->client, ds1307->offset, 8, buf);
+       if (tmp != 8) {
                pr_debug("read error %d\n", tmp);
                err = -EIO;
                goto exit_free;
        }
 
-       /* minimal sanity checking; some chips (like DS1340) don't
+       /*
+        * minimal sanity checking; some chips (like DS1340) don't
         * specify the extra bits as must-be-zero, but there are
         * still a few values that are clearly out-of-range.
         */
        tmp = ds1307->regs[DS1307_REG_SECS];
        switch (ds1307->type) {
-       case ds_1340:
-               /* FIXME read register with DS1340_BIT_OSF, use that to
-                * trigger the "set time" warning (*after* restarting the
-                * oscillator!) instead of this weaker ds1307/m41t00 test.
-                */
        case ds_1307:
        case m41t00:
                /* clock halted?  turn it on, so clock can tick. */
@@ -358,50 +802,72 @@ read_rtc:
                        goto read_rtc;
                }
                break;
-       case ds_1337:
-       case ds_1339:
-               break;
-       }
+       case ds_1340:
+               /* clock halted?  turn it on, so clock can tick. */
+               if (tmp & DS1340_BIT_nEOSC)
+                       i2c_smbus_write_byte_data(client, DS1307_REG_SECS, 0);
 
-       tmp = ds1307->regs[DS1307_REG_SECS];
-       tmp = BCD2BIN(tmp & 0x7f);
-       if (tmp > 60)
-               goto exit_bad;
-       tmp = BCD2BIN(ds1307->regs[DS1307_REG_MIN] & 0x7f);
-       if (tmp > 60)
-               goto exit_bad;
+               tmp = i2c_smbus_read_byte_data(client, DS1340_REG_FLAG);
+               if (tmp < 0) {
+                       pr_debug("read error %d\n", tmp);
+                       err = -EIO;
+                       goto exit_free;
+               }
+
+               /* oscillator fault?  clear flag, and warn */
+               if (tmp & DS1340_BIT_OSF) {
+                       i2c_smbus_write_byte_data(client, DS1340_REG_FLAG, 0);
+                       dev_warn(&client->dev, "SET TIME!\n");
+               }
+               break;
+       case mcp7941x:
+               /* make sure that the backup battery is enabled */
+               if (!(ds1307->regs[DS1307_REG_WDAY] & MCP7941X_BIT_VBATEN)) {
+                       i2c_smbus_write_byte_data(client, DS1307_REG_WDAY,
+                                       ds1307->regs[DS1307_REG_WDAY]
+                                       | MCP7941X_BIT_VBATEN);
+               }
 
-       tmp = BCD2BIN(ds1307->regs[DS1307_REG_MDAY] & 0x3f);
-       if (tmp == 0 || tmp > 31)
-               goto exit_bad;
+               /* clock halted?  turn it on, so clock can tick. */
+               if (!(tmp & MCP7941X_BIT_ST)) {
+                       i2c_smbus_write_byte_data(client, DS1307_REG_SECS,
+                                       MCP7941X_BIT_ST);
+                       dev_warn(&client->dev, "SET TIME!\n");
+                       goto read_rtc;
+               }
 
-       tmp = BCD2BIN(ds1307->regs[DS1307_REG_MONTH] & 0x1f);
-       if (tmp == 0 || tmp > 12)
-               goto exit_bad;
+               break;
+       default:
+               break;
+       }
 
        tmp = ds1307->regs[DS1307_REG_HOUR];
        switch (ds1307->type) {
        case ds_1340:
        case m41t00:
-               /* NOTE: ignores century bits; fix before deploying
+               /*
+                * NOTE: ignores century bits; fix before deploying
                 * systems that will run through year 2100.
                 */
                break;
+       case rx_8025:
+               break;
        default:
                if (!(tmp & DS1307_BIT_12HR))
                        break;
 
-               /* Be sure we're in 24 hour mode.  Multi-master systems
+               /*
+                * Be sure we're in 24 hour mode.  Multi-master systems
                 * take note...
                 */
-               tmp = BCD2BIN(tmp & 0x1f);
+               tmp = bcd2bin(tmp & 0x1f);
                if (tmp == 12)
                        tmp = 0;
                if (ds1307->regs[DS1307_REG_HOUR] & DS1307_BIT_PM)
                        tmp += 12;
                i2c_smbus_write_byte_data(client,
-                               DS1307_REG_HOUR,
-                               BIN2BCD(tmp));
+                               ds1307->offset + DS1307_REG_HOUR,
+                               bin2bcd(tmp));
        }
 
        ds1307->rtc = rtc_device_register(client->name, &client->dev,
@@ -413,16 +879,48 @@ read_rtc:
                goto exit_free;
        }
 
-       return 0;
+       if (want_irq) {
+               err = request_irq(client->irq, ds1307_irq, IRQF_SHARED,
+                         ds1307->rtc->name, client);
+               if (err) {
+                       dev_err(&client->dev,
+                               "unable to request IRQ!\n");
+                       goto exit_irq;
+               }
 
-exit_bad:
-       dev_dbg(&client->dev, "%s: %02x %02x %02x %02x %02x %02x %02x\n",
-                       "bogus register",
-                       ds1307->regs[0], ds1307->regs[1],
-                       ds1307->regs[2], ds1307->regs[3],
-                       ds1307->regs[4], ds1307->regs[5],
-                       ds1307->regs[6]);
+               device_set_wakeup_capable(&client->dev, 1);
+               set_bit(HAS_ALARM, &ds1307->flags);
+               dev_dbg(&client->dev, "got IRQ %d\n", client->irq);
+       }
+
+       if (chip->nvram_size) {
+               ds1307->nvram = kzalloc(sizeof(struct bin_attribute),
+                                                       GFP_KERNEL);
+               if (!ds1307->nvram) {
+                       err = -ENOMEM;
+                       goto exit_nvram;
+               }
+               ds1307->nvram->attr.name = "nvram";
+               ds1307->nvram->attr.mode = S_IRUGO | S_IWUSR;
+               sysfs_bin_attr_init(ds1307->nvram);
+               ds1307->nvram->read = ds1307_nvram_read,
+               ds1307->nvram->write = ds1307_nvram_write,
+               ds1307->nvram->size = chip->nvram_size;
+               ds1307->nvram_offset = chip->nvram_offset;
+               err = sysfs_create_bin_file(&client->dev.kobj, ds1307->nvram);
+               if (err) {
+                       kfree(ds1307->nvram);
+                       goto exit_nvram;
+               }
+               set_bit(HAS_NVRAM, &ds1307->flags);
+               dev_info(&client->dev, "%zu bytes nvram\n", ds1307->nvram->size);
+       }
 
+       return 0;
+
+exit_nvram:
+exit_irq:
+       rtc_device_unregister(ds1307->rtc);
 exit_free:
        kfree(ds1307);
        return err;
@@ -430,7 +928,17 @@ exit_free:
 
 static int __devexit ds1307_remove(struct i2c_client *client)
 {
-       struct ds1307   *ds1307 = i2c_get_clientdata(client);
+       struct ds1307 *ds1307 = i2c_get_clientdata(client);
+
+       if (test_and_clear_bit(HAS_ALARM, &ds1307->flags)) {
+               free_irq(client->irq, client);
+               cancel_work_sync(&ds1307->work);
+       }
+
+       if (test_and_clear_bit(HAS_NVRAM, &ds1307->flags)) {
+               sysfs_remove_bin_file(&client->dev.kobj, ds1307->nvram);
+               kfree(ds1307->nvram);
+       }
 
        rtc_device_unregister(ds1307->rtc);
        kfree(ds1307);
@@ -444,19 +952,10 @@ static struct i2c_driver ds1307_driver = {
        },
        .probe          = ds1307_probe,
        .remove         = __devexit_p(ds1307_remove),
+       .id_table       = ds1307_id,
 };
 
-static int __init ds1307_init(void)
-{
-       return i2c_add_driver(&ds1307_driver);
-}
-module_init(ds1307_init);
-
-static void __exit ds1307_exit(void)
-{
-       i2c_del_driver(&ds1307_driver);
-}
-module_exit(ds1307_exit);
+module_i2c_driver(ds1307_driver);
 
 MODULE_DESCRIPTION("RTC driver for DS1307 and similar chips");
 MODULE_LICENSE("GPL");